The bitter rift between Ed Miliband and his elder brother David now extends to
their wives, a new book about the sibling rivalry at the heart of the Labour
Party claims.

Ed Miliband’s wife, Justine Thornton, is said to have been deeply hurt by the frosty stance reportedly adopted by her sister-in-law Louise Miliband since his surprise decision to stand for the leadership last year.

Based on interviews with close friends and colleagues of the two men, the book depicts a deep and painful rift in the Miliband family which some fear will never heal.

It claims that an increasingly ill-tempered election campaign developed into a rancorous family schism, evident as much at children’s birthday parties as political meetings, to the distress of the men’s mother, Marion.

Despite his disappointment at failing to secure the Labour crown last September, the former Foreign Secretary David Miliband was careful to be gracious in defeat, the book says.

But as Ed walked back to his hotel room in Manchester, following the announcement the election result, his sister-in-law was less forgiving and “cut him dead”, the book claims.

It was, the authors – the Labour-friendly journalists Mehdi Hasan and James Macintyre – claim, “the start of a breakdown in the family”.

Miss Thornton and Mrs Miliband are themselves said to have fallen out quite personally, while the two men are portrayed as communicating largely through officials.

“Louise has been nasty towards Ed and Justine can't handle that,” a friend of the couple is quoted as saying.

It cites the Labour leader and his wife’s absence from his nephew’s sixth birthday party as evidence of the ill-feeling.

The same month Ed Miliband had spoken of hoping to see his brother at Christmas, joking that “no peacekeeping forces will be needed”.

In the event, the book says, David Miliband opted to fly to America to spend the holiday with his in-laws.

Despite public protestations that relations between the brothers are now on the mend, the book concludes: “The regular Sunday lunches where the two brothers would gather with their families and their mother – a summation of their once close-knit lives – are now a distant memory.”

It also alleges that there has been a long-standing personal clash between Ed Miliband and Ed Balls, his Shadow Chancellor, since both worked as advisers to Gordon Brown at the Treasury.

It claims that he could often be overheard "slagging off" Mr Balls and says that it was an “open secret” that they disliked each other.

Passages depicting the formative years of the man who hopes to become Prime Minister portray him as a precocious child addicted to computer games with an “amazing” gift for the Rubik's cube.

As a student at Oxford he is described as “geeky”, with few cultural interests other than watching Dallas, Neighbours and, occasionally, EastEnders.

More absorbed in politics than drinking or pursuing the opposite sex, he is recalled affectionately as a “terrible dancer”.

One contemporary is quoted as saying: “He didn't smoke or do drugs and he drank very little - I do remember him agonising over which chocolate bars to buy from the machine in the common room.”

The book recounts how several years later, after his election as an MP, he turned up at a party for members of the Commons 2005 intake and regaled them with a karaoke rendition of Neil Diamond's Sweet Caroline.

While his decision last year to stand for the leadership has been widely interpreted as a last-minute, unexpected move, the book portrays him as having a long-standing determination, unafraid to bypass his brother's ambitions.

One friend asked him why he was challenging for the Labour crown, adding : “I assume it's because you can't have two Milibands in a row.” He is said to have replied: “That's exactly it.”

It also claims that the pair now do not agree even on exactly when it was that Ed Miliband broke the news of his candidacy to his elder brother – a moment depicted as a ”Biblical act of fratricide”.

Despite the public protestations of fraternal loyalty during the campaign, Ed Miliband’s aides are said to have blamed his brother’s supporters when he was depicted as “Red Ed” or “Forrest Gump”.

They replied in equal measure, depicting his brother as a robot with placards reading “Ed speaks human”.

One unnamed ally sums it up saying: “It was hardball.”

Ed: The Milibands And The Making Of A Labour Leader by Mehdi Hasan and James Macintyre is published by Biteback.